Patent Document 1 describes a roller bearing having spacers interposed between rollers. In such a type of roller bearing, its load capacity can be improved without significantly reducing the rotational performance by interposing the spacers, in place of a cage, between the rollers. Specifically, the spacers can prevent adjacent rollers from coming into contact with each other, and tensile stress associated with changes in separation distance between the rollers is not exerted on the spacers provided separately and independently. Therefore, the size and number of the rollers can be increased.    [Patent Document 1] Japanese Patent No. 3549530.